Containers provided with electrodes are particularly used in applications in which the reaction batch must be acted upon with an electric voltage pulse, such as for example electroporation, electrofusion and electrostimulation of living cells. Containers of this type can also have a plurality of reaction spaces, wherein each reaction space can be provided with electrodes. These containers are generally designated as multiwell plates, microtitre plates or multiwells. They are primarily used in biochemical and pharmaceutical applications, in which a multiplicity of reaction batches must be tested at the same time. In this case, the endeavour to provide a number of reaction spaces, for example 384, which is as large as possible, particularly in the case of HT analyses (HT=high throughput), is to be recognised, as here a multiplicity of samples should be tested in the shortest time possible.
The known containers usually consist of a plurality of reaction spaces which in each case have two electrodes which are in contact with the reaction batch, for example a cell suspension, in the reaction space. The two electrodes of a reaction space generate an electric field and a current flow when an electric voltage is applied in the interior of the reaction space, wherein they have different potentials and/or polarities in the case of direct current, for example. The electrodes with the same polarity, that is to say for example all cathodes and/or all anodes, of the different reaction spaces are in this case either constructed in one piece or electrically coupled to one another, so that they can be connected to the voltage source via a common electrical contact.
The loading of the reaction spaces of such containers with voltage pulses takes place by means of special switching arrangements which comprise one or two storage device(s) for storing electric charges. The storage devices are in each case capacitors which are charged to a predetermined electric charge and can output defined voltage pulses by means of targeted discharge. The storage devices are connected to electric switches, for example power semiconductors, by means of which the targeted discharge of the storage devices is switched. The use of two storage devices allows the output of two short voltage pulses that follow one another or merge into one another, which can be of advantage in the case of the electroporation of certain cell types. Contact pins are generally used for the electrical contacting of the electrodes of the containers, which contact pins are arranged on arms or plates and are manually or automatically brought into contact with the electrodes.
A container with a plurality of reaction spaces is known from EP-A-1 577 378, which container comprises a plurality of modules. Each module in this case has two rows of reaction spaces arranged in parallel, which reaction spaces in each case have an electrode pair, consisting of a first and a second electrode, for applying an electric voltage for generating an electric field within the reaction space. The first electrodes arranged on the same side of the different reaction spaces of a row are electrically conductively coupled, whilst the second electrodes of a reaction space can be electrically separately connected. In this case, the oppositely arranged first electrodes of different reaction spaces of adjacent rows are also electrically conductively coupled. In this known container, all reaction spaces are separately or individually addressable, that is to say each separate reaction space can be loaded with a voltage pulse independently of the other reaction spaces.
A container with a plurality of reaction spaces is further known from U.S. Pat. No. 5,183,744, in the case of which container the separate reaction spaces are likewise separately addressable. Each separate reaction space of this known container is provided with two electrodes, wherein in each case one of the electrodes of an electrode pair is electrically coupled to the corresponding electrodes of the other reaction spaces of a row of reaction spaces. The other electrode of the electrode pair in each case of a reaction space is separately electrically contacted, so that each separate reaction space can be individually loaded with a voltage pulse. U.S. Pat. No. 5,183,744 further discloses a container with a plurality of reaction spaces, in the case of which container the electrodes of the separate reaction spaces are connected to one another in the manner of a matrix. The matrix is in this case formed by conductor tracks which cross, wherein the conductor tracks are separated from one another at the respective crossing points by an insulating layer. The separate layers are connected via contact points to the conductor tracks so that each separate reaction space is theoretically addressable. Namely, if a voltage is applied to two crossing conductor tracks, then theoretically only the reaction space which is connected to these two conductor tracks is loaded with the voltage. It has been established in practice however that parasitic currents arise in the case of such a matrix, so that electric current also unintentionally flows through other reaction spaces. A solution of this type therefore has the disadvantage that undesired side effects occur, which significantly impair the efficiency and the reproducibility of the methods carried out with containers of this type.
WO 2005/044983 A2 likewise discloses a container with a plurality of reaction spaces, in the case of which container each reaction space has an electrode pair for applying an electric voltage. The electrodes are in this case, as already known from U.S. Pat. No. 5,183,744, connected to one another by means of crossing conductor tracks in the manner of a matrix. Here as well, parasitic currents and thus undesired side effects consequently cannot be prevented.
US 2007/0231873 A1 discloses a container with a plurality of reaction spaces, in the case of which container each separate reaction space is provided with two oppositely arranged electrodes. However, in the case of this container, the separate reaction spaces are not individually addressable, rather only separate groups which in each case consist of a plurality of reaction spaces, are simultaneously loaded with a voltage pulse.
A container with a plurality of reaction spaces is further known from WO 2007/094947 A2, in the case of which container each reaction space has two oppositely arranged electrodes. However, this known container also has the disadvantage that the separate reaction spaces are not individually addressable here, but rather merely addressable in groups.
All known containers have the disadvantage that either the reaction spaces are not separately addressable or the containers have a high number of electrodes overall, wherein the number of electrodes is twice as high as the number of reaction spaces. A reduced active and passive volume of the separate reaction spaces results from this in the case of the given dimensions of the container.